This invention relates to laser systems and in particular to multi-wavelength laser systems.
Use of lasers for medical purposes is well established. Lasers are used extensively for cosmetic purposes such as hair removal, vein treatment, skin rejuvenation, treatment of telangeatesia and treatment of port wine stain. Each of these treatments is preferably performed with a laser producing laser pulses at a wavelength chosen to be most effective for the particular treatment. For example, a Nd:YAG laser operating at 1064 nm may be used for hair removal and certain types of vein treatment. A Nd:YAG laser operating at 1320 nm may be used for skin rejuvenation and micro skin surgery. Treatment of port wine stains is usually performed using a dye laser operating at a wavelength of 577 nm. Lasers used for treatment of small surface veins do not work very well for treatment of larger deeper veins. As a consequence a medical facility offering a variety of laser-based cosmetic services in the past has been required to acquire and maintain several separate laser systems. This is expensive.
Some wavelengths are very preferentially absorbed in a particular type of tissue such as when the tissue contains a particular chromophore that has a peak or reletively high absorption at the particular wavelength. Use of a laser beam matched to a peak or relatively high absorption in tissue to treat the tissue is referred to as xe2x80x9cselective thermolysisxe2x80x9d. Some wavelengths are absorbed relatively uniformly in tissue and when these wavelengths are used to treat the tissue it is referred to as xe2x80x9cnon-selective thermolysisxe2x80x9d.
What is needed is a single laser that can produce simultaneously laser light at a variety of wavelengths needed in medical facilities specializing is cosmetic care.
The present invention provides a single laser system that operates at any one or any combination of at least five wavelengths each of which are important to medical facilities offering laser cosmetic services. It includes appropriate laser optics and a crystal rod configured to produce a first pulsed laser beam, and appropriate laser optics and a second crystal rod configured to produce a second pulsed laser beam. Both rods are pumped simultaneously preferably from the same pump source. Beams from each of these lasers are frequency doubled using frequency-doubling crystals to produce third and fourth laser beams. The frequencies of the first and second beams are also combined in a sum frequency generating crystal to produce a fifth laser beam. In a preferred embodiment the first and second laser beams are produced using YAP:Nd crystals with wavelengths of 1079 nm and 1341 nm. The third and fourth laser beams at 539.5 nm and 670.5 nm are produced using KTP frequency doubling crystals and the fifth laser beam at about 598 nm is produced using a KTA sum frequency crystal. Thus, five different beams are produced with this laser system. All or any combination of these five beams are preferably combined by coupling them into a single optical fiber so that the beam can be easily transmitted to the place of treatment.